I bought a Deltron from Amazon soon after getting my car 33 months ago. I hook it up when I know the car isn't going to be driven for more than a week. Never a problem, although obviously an electrical outlet is needed for the charger. I never had the need for this with any other car, and I can't say I'm happy about it. However, having seen the cost of replacement batteries plus 'registering' (never needed that requirement on any other car either), the charger was a significant bargain.